"Ever since the remote control's co-inventor Robert Adler passed away [in March], I've wanted to own one of the first remote controls. After trolling through eBay every now and then, I finally have in my hands a piece of the history of the button. But there's a mystery: which piece?" Entertainingly written piece on the world's first remote controls. I totally enjoy the simplicity of the ultrasonic remote: "All these early remotes are purely mechanical. No batteries at all. When you push the button, a small hammer strikes an aluminum rod, triggering a sound above our hearing range that's picked up by the TV. Each rod is a different length, thus a different frequency, thus distinguishable by the TV." Brilliant.